Currently, there are products in the consumer market that can detect baby-breathing movement using different sensing technology.
One method is based on piezoresistive pressure sensor pads that are placed beneath the mattress for detecting movements. This type of pressure sensor pad may include a micro-machined silicon diaphragm with piezoresistive strain gauges diffused into it, such as fused to a silicon or glass backplate. Pressure induced strain increases the value of the radial resistance. This resistance change can be high as 30%. The resistors are connected as a Wheatstone Bridge Circuit, the output of which is directly proportional to the pressure applied to the pressure sensor pads.
The pressure sensor pads may detect movement of the baby sleeping on the mattress, including breathing action by baby. But such sensors often provide false alarms that may arise from high sensitivity of the pressure sensor pad to any surrounding vibrations transmitted to the pressure sensor through the bed frame structure. Further, such pressure pad would not work properly on a spring-based mattress. In addition, although such pressure sensor pad is also able to pick up breathing action, it does not provide any breath count because it is not able to differentiate the type of movements occurring on the bed.
There exists another sensor that is based on the properties of piezo film (strip of piezoelectric PVDF polymer film) as a dynamic strain sensor to detect the breathing rate of an infant. Such sensor uses a PVDF-monitor device clipped to the waistband of the baby's diaper. When the baby breathes, its stomach movement causes strain to the piezo film materials, which generates the signal for detecting breathing movements. Such a sensor, however, also provides false alarms arising from bad contact between a diaper or nappy and a body of a baby, especially if the baby body circumference is small or the diaper or nappy is too large or too loose for the baby. Further, such a sensor is also not able to provide any breath count; only detects for non-breath movement.